LHC machine plans

1. LHC machine plans Mike Lamont Machine plans - CMS startup workshop

2. 2007 Sectors 5-6, 6-7, 1-2 & 2-3: - baseline commissioning of main circuits to 1.1 TeV - minimal circuit set Machine plans - CMS startup workshop

3. End 2007 Oct 450 GeV HWC ACCESS TESTS 450 GeV HWC Operations testing Nov Machine Checkout (Access, Vacuum, Equipment Tests, Controls, Cycle (partial), Beam dump, Interlocks and INB) Beam Commissioning at 450 GeV 16 days beam time estimated Dec Calibration run (Collisions at 450GeV + ramp commissioning etc.) Machine plans - CMS startup workshop

4. 450 GeV – Calibration Run • Operations’ aims: • Commission essential safety systems • Commission essential beam instrumentation • Commission essential hardware systems • Perform beam based measurements to check: • Polarities • Aperture • Field characteristics • Establish collisions • Provide stable two beam operation at 450 GeV • Interleave collisions with further machine development, in particular, the ramp. Should provide a firm platform for eventual commissioning to 7 TeV and provide adequate lead time for problem resolution. Machine plans - CMS startup workshop

5. Machine Configuration • Optics: • β*= 11 m in IR 1 & 5 • β*= 10 m in IR 2 & 8 • Limited by triplet aperture • Crossing angles off • 1, 12, 43, 156 bunches per beam • Separation bumps - two beam operation • Shift bunches for LHCb • 4 out of 43 bunches, or 24 bunches out of 156 • Solenoids & Exp. Dipoles etc. off (to start with) Machine plans - CMS startup workshop

6. 450 GeV Beam Commissioning: Phases Machine plans - CMS startup workshop

7. Beam • Pilot Beam • Single bunch, 5 - 10 x 109 protons, reduced emittance • Pilot++ • Single bunch 3 to 4 x 1010 protons • 4, 12 bunches etc. pushing towards… • 43,156 bunches • 3 to 4 x 1010 ppb Machine plans - CMS startup workshop

8. Time Given an operational efficiency of 60%, this gives an elapsed time of about 26 days. CAVAET: MACHINE AVAILABILITY Some opportunities for parallel development and parasitic studies… Machine plans - CMS startup workshop

9. 450 GeV - Performance Reasonable Maximum Several days • Assuming 450GeV inelastic cross section 40 mb • Assuming 450GeV cross section W → lν 1 nb • Assuming 450GeV cross section Z → ll 100 pb Machine plans - CMS startup workshop

10. Calibration Run 2007 • 6 weeks beam time • 3 weeks beam commissioning • Essentially single beam, low intensity for the most part • 3 weeks collisions • Single bunch initially, with staged increase to 156 x 4 x 1010 (+) • Luminosities: 1.3 1028 to 2.6 1029 cm-2s-1 (+) • Interleafed with low intensity single beam MD • Initial ramping tests to 1.1 TeV etc. Machine plans - CMS startup workshop

11. 450 GeV Beam Spot - Longitudinal • RMS bunch length at 7 TeV = 7.55 cm, 16 MV • Nominal 450 GeV • RMS bunch length = 11.24 cm • RF voltage = 8 MV • For coast will raise voltage to 16 MV – increase Δp/p and shorten bunch length: • Δp/p (2 σ) 0.88e-3 to ~1.1e-3 with concomitant decrease in bunch length • Can shift interaction point in units of ± 0.375 m ± cms. Machine plans - CMS startup workshop

12. Beam spot – transverse • Bigger beams at 450 GeV • 290 µm at β* = 11 m. • 277 µm at β* = 10 m. • 2 challenges: • Colliding the beams: should be able to get them within 150 µm using BPMs • Orbit stability: feedback to be commissioned • Vertex position • Transverse: 1 mm run-to-run, 3 mm long term • Absolute position: approx. ± 400 µm from BPMs Transverse beam size from one of: Synchrotron Light Monitor, Rest Gas Monitor or Wire Scannerplus optics measurements Machine plans - CMS startup workshop

13. Relative Luminosity Measurement • Low luminosity will be straining bounds of machine luminosity monitors (LBL ionization chambers - BRAN) • Low event rates of high energy neutrons in BRAN • Background, Signal/Noise • Initial collisions with single bunch 1.1 x 1011 to give BRAN something to see. • Other ideas: • Beam-beam coupling signal from high sensitivity BPM • Schottky • Scintillators [machine] Machine plans - CMS startup workshop

14. Background Beam gas interactions and beam halo muon/hadron rates • Residual gas within experiments • Baked out – low rates • Residual gas in LSSs • Gas pressure in adjacent cold sectors • Relative high pressures, elastic scattering • Inefficiency of cleaning in IR7 & IR3 Nikolai Mokhov See: M Huhtinen, V. Talanov, G. Corti et al Machine plans - CMS startup workshop

15. Vacuum – 450 GeV A. Rossi LPR 783 The 450 GeV run will be stage 0. No conditioning, minimal pump-down time in some sectors. Static vacuum. Potentially some LSSs un-baked - no NEG activation Vacuum life time shall be greater than 35 h and 50 h for 2007 and 2008 respectively Machine plans - CMS startup workshop

16. Halo • Scrape in the SPS, collimate in the transfer lines • Expect halo generation from • RF noise • Intra Beam Scattering • Optics mismatch • Beam-gas • Poor parameter control (tune, chromaticity), poor lifetime, stream particles to aperture limit • Nominally this is cleaned by the collimation system with the resulting tertiary halo potentially finding its way to the experiments insertion – and the tertiary collimators Vadim Talanov & team plan detailed studies, given scenario of collimator operation at the 450 GeV start-up (loss maps etc.) Machine plans - CMS startup workshop

17. 450 GeV: Collimation I • With low beam intensity: • Primary collimators: 6σ • Secondary collimators: out • Tertiary collimators: out • Absorbers: out • TCDQ: 10σ • TDI: out • Lower intensity • Lower energy • Bigger beams • Un-squeezed • Aperture limitation is the arcs & DS Machine plans - CMS startup workshop

18. 450 GeV: Collimation II • With an optimistic beam intensity we might see: • Primary collimators: 5.7σ • Secondary collimators at 6.7σ • Tertiary collimators: out • Absorbers: out • TCDQ: 9σ • TDI: 6.8σ Un-squeezed – tertiary collimators out – aperture limit in the arcs – would expect low halo losses in IRs TDI – IP2(out after inj.) Machine plans - CMS startup workshop

19. Who knows… Helmut Burkhardt Machine plans - CMS startup workshop

20. 2008(briefly) Machine plans - CMS startup workshop

21. Staged commissioning plan for protons@7TeV 2008 Stage I II III No beam Beam 2009 III Beam No beam Machine plans - CMS startup workshop

22. 2008 Should look something like… Hardware commissioning to 7 TeV Machine Checkout 1 month Commissioning with beam 2 months Pilot Physics 1 month Provisional Machine plans - CMS startup workshop

23. Beam Commissioning: usual stuff.. Machine plans - CMS startup workshop

24. Full commissioning to 7 TeV Should benefit from 450 GeV run Given 450 GeV run and reasonable machine availability might expect first 7 TeV collisions in around 2 months RHIC 2000:- First beam April 3rd- First successful ramp: June 1st- First collisions June 12th Machine plans - CMS startup workshop

25. 7 TeV commissioning • Around 2 months elapsed time to establish first collisions • Mostly pilot++, low intensity, single beam, alternate rings • No crossing angle • No squeeze: β* = 17 – 10 – 17 – 10 m. • Stage 1 vacuum conditions • Experiments & LSSs should be baked out • Other LSSs potentially not • See LHC project note 783 • Collimation during initial commissioning • Minimal collimation scheme under discussion, probably primary & secondary with no tertiary/absorbers • Again expect low halo loss in experiments • First collisions • Single bunch • Un-squeezed • Pilot physics Machine plans - CMS startup workshop

26. Pilot physics Leading into 75 ns running Machine plans - CMS startup workshop

27. Conclusions • 450 GeV calibration run • 3 weeks single beam machine commissioning • Low beam current but potentially interesting vacuum conditions • Minimal collimation scheme • 3 weeks collisions with the hope to push over 1029 cm-2s-1 • Detailed BG studies planned • 7 TeV • 6-8 weeks single/two beam machine commissioning • Low beam current but potentially interesting vacuum conditions • Un-squeezed initially, with minimal collimation • Still work to do after first collisions – pilot physics • Detailed BG studies already performed and on-going http://cern.ch/lhc-commissioning/ Machine plans - CMS startup workshop